A small band of believers urges NASA to take its next step—onto an asteroid.

None of these missions requires more time in space than the six months astronauts typically spend on the space station. A Mars round trip requires three years. Lu’s own return after six months of weightlessness was easy, he says. Having spent two hours on aerobic and strength training every day in orbit—“and we did it religiously”—he was able to stand up on the Kazakh plain immediately after landing there in a Russian Soyuz capsule. “I was 70 percent normal within a few days, and 90 percent within three weeks,” he says.

In other words, one of the big unknowns about a Mars trip—how the human body will react to three years of weightlessness—is no concern at all for an asteroid mission. And once they reach their destination, the astronauts won’t have to adapt to one-third Earth gravity, as they would on the surface of Mars. Amid all the discussion of “hopping on and off,” Lu makes a key point. “People get the misconception that we’ll land on an asteroid,” he says. “We won’t. It’s almost zero-G. You’re not going to walk on that surface.” Working around an asteroid would in some ways be like floating around the space station, which is also the size of a football field. Astronauts would likely perform asteroid “walks” using jet backpacks or tethers, possibly firing small anchors into the surface for leverage.

What about the cramped nature of a six-month voyage inside Orion, with a habitable volume only one-fifth that of the space shuttle? Lu shrugs it off. “If I knew I was going out to an asteroid and back, I’d live in something half that size. You ask around the Astronaut Office who wants to go. You’ll have a line out the door.”

That comes as no surprise to Bob Farquhar, a former mission designer for such robotic spacecraft as NEAR Shoemaker, Messenger to Mercury, and New Horizons to Pluto. He’s now a fellow at the National Air and Space Museum. “I don’t doubt you’d have guys volunteering to climb inside Orion for six months,” he says. “You could get astronauts who’d volunteer for a one-way mission to Mars. But that’s not the way we do it.”

In the Asteroid Underground, Farquhar is something of an elder statesman and is known for his outspokenness. Having taken part in a recent feasibility study for the International Academy of Astronautics that looked at different options for moving beyond Earth orbit, he doesn’t like the idea of making do with existing Constellation hardware for a stripped-down asteroid mission. “You’d need a transfer vehicle,” he says. “Something big and roomy. And you don’t want it in low Earth orbit all the time.” Instead, he would park an interplanetary, or inter-asteroidal, transfer vehicle at the L2 libration point, about a million miles outside Earth’s orbit, where the gravitational pulls of the sun and Earth are balanced. The transfer vehicle would pick up the crew members in Earth orbit, take them to an asteroid (or, someday, Mars), and then, at journey’s end, return them to Earth orbit.

However the missions are designed, astronauts who travel to an asteroid will spend months outside Earth’s magnetic field, which shields space station crews from harmful space radiation. An asteroid-bound ship would need heavy shielding: perhaps a water or hydrogen jacket, or thick plastic composites. Another unknown, and another technology to develop.

Despite such challenges, the Asteroid Underground has won converts, in part due to a lack of enthusiasm among many in the space advocacy community for NASA’s current plans to return to the moon. Farquhar has been among the most vocal critics. “We need to reexamine this whole lunar thing,” he says. “I think you could skip the lunar landing and lunar bases. They’ll eat up NASA’s budget for the next 50 or 60 years.” In fact, the price tag for an asteroid mission would almost certainly be less than the cost of a lunar landing.

Farquhar was one of 50 thinkers who attended an invitation-only workshop at Stanford University last February, sponsored by the Planetary Society and titled “Examining the Vision: Balancing Science and Exploration.” The group included scientists, aerospace executives, space advocates, NASA staff, and former astronauts. Press reports prior to the meeting made it sound like the Asteroid Underground planned an insurrection against NASA’s lunar program. That led agency administrator Mike Griffin, who has fought to win support in Congress for Constellation, to lash out against those who would push destinations other than NASA’s approved next step, the moon. The controversy may explain why, instead of arguing strongly for an asteroid mission, the statement that came out of the workshop merely called for sustained human exploration to Mars and beyond, which would be done via the moon and “other intermediate destinations.” The word “asteroids” was never mentioned.

Farquhar calls the statement “wishy-washy” and says the meeting was co-opted by NASA attendees. “The Stanford conference didn’t accomplish what [the asteroid advocates] had hoped, which was to take another look at the whole program. The organizers were trying to have an ecumenical experience, inviting people from throughout the industry. There turned out to be more of the faithful than the dissidents. I thought it was a flop.”

For the time being, it seems, the Asteroid Underground has suffered a setback. But the prospect of political change (a new president not wedded to the moon plan), and not just in the United States, gives asteroid mission advocates hope that their fortunes will soon improve. “We might wind up around 2020 with the Chinese about to set foot on the moon, possibly with the Russians,” says Jones. “But we’ll have something else in our back pocket—on our way to an asteroid, we could wave at them down on the lunar surface and say, ‘We did that 50 years ago.’ ”